JP2556678B2 - Filtration screen - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to screens for use in filtration processes, and in particular for filtering particle-containing suspensions or slurries.

BACKGROUND OF THE INVENTION Generally, in a typical filtration process of the type shown, a plurality of different sized mesh filter elements are mounted one on top of the other, such as in a vibrating cradle. Each wire mesh screen is tensioned across the cradle using a fixed hook. Alternatively,
Each one mesh screen may be mounted and possibly stretched within a screen insertable into the cradle.

Various screen cloths are stretched within a frame from which a screen for use in a vibrating screen device is constructed according to British Patent Specification No. 15
Known from 26663. In this configuration, by carefully selecting the screen cloth mesh dimensions and positioning one screen cloth over the other on the curved inner frame member,
Such improved vibrating screens have been created, and such vibrating screens are less clogged than previously designed screens.

Of course, it is necessary to ensure a high level of tension on the screen cloth, and this has been achieved in the previous design of GB1526663 by using a bent stringer, which allows the stretched cloth to Form an arched morphology.

In this first design, there is little tendency for particles to get into the gaps between screen cloth gaps due to the slight relative movement between the cloths as a result of vibrations during the screening operation. Such vibrations tend to cause the upper screen cloth to move slightly with respect to the lower screen cloth, thereby causing the particles to dissipate, as described on page 3, line 40 of the specification No. 1526663. Can fall through them. The claimed self-cleaning features for this screen appear to be achieved by relative oscillatory motion in the plane of the size of two screen cloths when the screen is vibrated. This relative movement is brought about by the arched state of the screen cloth and the fact that one overlies the other.

Constructing a screen from a rigid frame and stretching two screen cloths across the frame, one above the other, the lower screen cloth having a coarser mesh than the upper screen cloth And it is known from British Patent Specification No. 1578948 that the lower screen cloth is more strongly tensioned than the upper screen cloth.

Because the configuration of this second design is a simpler form,
Differential tension can be achieved in that the screen cloth is stretched to the point where tension is needed and is placed in the proper location on the frame with a suitable adhesive that holds the differential tension in the screen cloth. .

OBJECT OF THE INVENTION It is an object of the present invention to provide an improved filter screen, for example a filter screen that can normally be used in vibrating cradle.

The present invention also seeks to provide a screen which is very simple in construction and which can be used in a vibration screening device having self-cleaning properties.

SUMMARY OF THE INVENTION According to the present invention, the following filter screen is provided.

A filtration screen for mounting on a vibration screening device, comprising: a first wire mesh cloth and a second wire mesh cloth having a mesh size and tension different from that of the first wire mesh cloth, One wire mesh cloth overlies the second wire mesh cloth, the first and second wire mesh cloths
Both of the wire mesh cloths are fixed to a frame so as to keep these mesh cloths taut, (i) the frame has the first and second wire mesh cloths joined together and a plurality of Of the sheet metal plate (88) with material removed by punching to leave the aperture of (ii) the edge region (90,92) of the aperture projecting from the underside of said plate (88) and by punching. The protruding edge regions (90,92) formed as a result of metal removal extend substantially perpendicular to the plane of the plate and reinforce the edge of the aperture and increase the overall stiffness of the plate. And a filtration screen.

The invention is not limited to using only two screen meshes; additional meshes having the same or different mesh sizes and having the same or different tensions may be used on top of the two meshes initially mentioned. Can be incorporated by coupling to.

The second and third meshes are preferably tensioned, each to a lesser degree so that the second mesh is tensioned by a lesser amount than the first mesh and the third mesh Mesh is tensioned to a lesser extent than the second mesh.

The screen dimensions are usually the same in both warp and weft directions and are described by a number, such as 100, which indicates the number of warp or weft strands per inch.

In a preferred embodiment, the first mesh has a mesh size in the range of 10 to 30 and the second mesh has a size of 20 to 30.
The third mesh has a mesh size in the range of 325 and the third mesh has a mesh size in the range of 30 to 325.

The numbers 40 and 325 are shown as typical maximums and minimums, but the invention is not limited to screen cloths of 10 to 325 mesh, screen cloths outside that area having a particle size It may be used accordingly.

In order to give the first screen cloth the necessary rigidity, it is typically tensioned in the range of 50 to 90% of its ultimate tensile strength and the second screen cloth is Is conveniently tensioned in the range of 10 to 80% of its ultimate tensile strength, and the third screen cloth is conveniently
It is tensioned in the range of 0 to 75% of its ultimate tensile strength.

In a typical triple cloth screen, the tension of the first cloth is 70%, the tension of the second cloth is 60% and the third is of the ultimate tensile strength of the material from which the cloth is formed.
The cross tension is 55%.

DETAILED DESCRIPTION OF THE FIGURES FIG. 1 is in accordance with the invention in the form of a plate 88 made of sheet steel with punched apertures (sheet steel), as best seen by comparing FIGS. 1 and 2. A support part, ie, a frame, is shown.
Not only does each of the punches reveal an aperture, but two ledges of metal also project below the aperture, such as 90 and 92 in FIG. 2, which reinforce the edge region of the aperture. The presence of these ledges bent down increases the overall stiffness of the sheet material 88.

Two or more screen meshes 94, which are tensioned differently as needed, are bonded to the top surface of the sheet material 88 with a suitable adhesive, as shown at area 95.

In each of the embodiments described herein, the screen mesh may be of woven wire, which is tensioned before they are bonded to the selected support, which selected support assembly. It serves to maintain different tensions in the mesh.

If the rigidity of the plate 88 is insufficient to ensure that the desired tension of the screen cloth is maintained, then it will be paired with the upper and lower elongated supports 96, 98, 100, 102, as shown in the cross-sectional view of FIG. And 104 may be supported by the vibrator. The protrusions of rubber or other elastic material
It fits nicely into the ends of the supports 96, 98, etc., as shown at. Conveniently, the support is aligned with the bonded area 95.

All of the screens described herein, whether rigid or not, are intended to be tightly clamped to a vibration screening device in use.

In a typical screen shown in cross section in Figure 4, 3
All of the cloths 210, 212, 214 are formed from woven stainless steel wire. However, the present invention is not limited to the use of stainless steel wire, nor is it limited to the use of common materials for all this screen cloth, and for different cloths, different materials may be used, or 1 of 3 crosses
The use of materials other than stainless steel wire for one or all is also contemplated.

Thus, for example, the first screen may be formed from woven stainless steel wire and the second and third screens may be formed from woven nylon monofilament strands. (Nylon is a registered trademark).

The cloth is joined to a steel frame surrounded by straight lines, the sides of which are formed from angled parts. These side members are shown at 216 and 218. The bond is made at 220 with epoxy resin, but it should be understood that other suitable adhesives may be used and the invention is not limited to the use of any suitable adhesive material. is there.

The resulting screen has a vibrating screen as disclosed in British Patent Specification 1575312 by clamping the screen along at least two edges and, if desired, along all four edges. Can be fitted to the device. However, the invention is not limited to use in such devices.

The screen of FIG. 4 is composed of the following steps. That is, a first relatively coarse mesh screen cloth 214 is taut over a frame having side members 216 and 218, and a peripheral area of the screen cloth is connected to the flanges of the side members 216, 218 and surrounded by a straight line. Adhesive is applied to the edge region to bond to a similar end member (not shown) of the assembled frame, and a second screen cloth 212 is laid over the first cloth and the second screen cloth 212 is overlaid. The screen cloth has a relatively fine mesh, and the second cloth is tensioned to a degree smaller than the tension of the first coarse mesh cloth 214, both of the second adhesives are applied, and the same manner as the first embodiment. The second screen mesh is joined with the third screen cloth, and thirdly, after the adhesive is hardened, the third screen cloth 210 having a finer mesh than the second cloth 212 is laid on the second screen cloth. The third screen cloth 210 is tightened to a degree smaller than that of the second cloth 212, and a third adhesive layer is applied around the periphery of the third screen cloth 210 to apply the third screen cloth 210 to a predetermined area. Lock in position.

If desired, three cloths are laid separately on the frame and the adhesive is applied in a single step.

 The adhesive may be a thermosetting adhesive.

FIG. 5 is an enlarged view of the screen cloth of FIG.
FIG. 6 is a cross-sectional view of two of the 210 and 212 layers.
The third cross 214 is not shown. Cross 210 and 212
The screen mesh dimensions of are substantially the same,
And in the static mode, the two cloths lie on top of each other as shown in Figure 5 (a) and the warp and weft strands of different cloths are generally linked substantially as shown. are doing. 5 (a) and 5
In Fig. (B), the relationship between the wire diameter and the wire spacing is not intentionally scaled.

Due to the higher tension of the lower mesh and the higher tension of the upper mesh, these meshes separate when the screen moves downwards and then re-engage when the movement reverses, thereby otherwise Particles are formed on the upper mesh that would clog the openings in the upper mesh. This particle should be removed.

However, in addition, the wires in the lower mesh insert most of the openings in the upper mesh, thus preventing solids that would normally stay in the openings in the upper mesh from remaining in the lower mesh by repeated infiltration into the openings in the upper mesh. It is obviously important to be able to.

The thickness of the upper mesh also seems to be important, because the mesh is such that particles close to the overall dimensions of the upper mesh (which would normally clog the upper mesh) but the repeated infiltration of the lower mesh wire. This prevents penetration into the upper mesh opening far enough so that it will remain.

Because of the controlled differential tension between the meshes, the combined effects of slapping and wirehole penetration enable highly effective self-cleaning actions to be performed.

Tight control over the different tensions of various screen wires, which is important in obtaining a consistent and predictable effect by fixing the mesh by gluing the edges of the mesh to the rigid frame, and Allows maintenance of those tensions.

[Brief description of drawings]

FIG. 1 shows a punched plate support according to the present invention. FIG. 2 is a sectional view taken along line 15-15 of FIG. FIG. 3 is a sectional view taken along the line XVI-XVI in FIG. FIG. 4 is a cross-sectional view of a screen constructed according to the present invention. FIGS. 5 (a) and 5 (b) show in enlarged cross section how differential tension causes the two meshes to move independently during vibration. In the figure, 210 and 212 are wire mesh cloths, 88
Is a sheet metal plate, and 90 and 92 are protruding edge regions.

Claims (2)

(57) [Claims] 1. A first wire mesh cloth (210),
A second wire mesh cloth (21) having a mesh size and tension different from that of the first wire mesh cloth (21
2) A filter screen for mounting on a vibration screening device, comprising: (1), wherein the first wire mesh cloth (210) is the second wire mesh cloth (2).
12) overlying and both said first and second wire mesh cloths are secured to a frame to keep these mesh cloths taut; (i) said frame comprises: And a sheet metal plate (88) having a second wire mesh cloth joined thereto and having material removed by punching so as to leave a plurality of apertures, (ii) an edge region (90, 92) of the aperture is Protruding from the underside of the plate (88) and formed as a result of metal removal by punching, the projecting edge regions (90,92) extend substantially perpendicular to the plane of the plate and reinforce the edge of the aperture. A filter screen characterized by increasing the overall rigidity of the plate. 2. A filter screen according to claim 1, further comprising an elongated support (96,98,100,102,104,106) aligned with the combined regions (95) of the first and second wire mesh cloths. .